The present invention relates generally to pharmaceutical compositions comprising microparticles suspended in micelle. More particularly, the microparticles comprise at least one pharmaceutically-active agent, at least one water soluble or miscible phospholipid, at least one lipid soluble or miscible phospholipid, at least one water soluble or miscible sterol, at least one non-ionic surfactant having an HLB value of about 15 or greater, and at least one non-ionic surfactant having an HLB value of about 6 or less, and the microparticles are suspended in micelle in at least one water soluble or miscible fatty acid having a chain length of C.sub.14 or less. This invention also relates to a method of preparing such compositions, methods of therapeutically treating various illnesses and conditions with such compositions, and methods of delivery of such compositions to human beings.
By binding a pharmaceutically-active agent (e.g. insulin) in accordance with this invention, enhanced bioavailability and bioactivity results from the bound pharmaceutically-active agent. For example, after oral or transdermal administration of the embodiment of this invention where insulin is the pharmaceutically-active agent, the composition is channeled into the liver, where the initially protected insulin is gradually released, mimicking an endogenously secreted insulin as found in human beings. An exogenous insulin, for example, has been successfully delivered by routes other than parenteral injection. The compositions of this invention may be applied by rectal, buccal, sublingual, intranasal, intrapulmonic, ocular or by other means of administration for management of disorders, for example diabetes mellitus. The compositions may be delivered selectively, after parenteral infusion, oral, transdermal, or other means of administration to achieve precise targeting of the pharmaceutically active agent to a given organ or tissues as a slow, controlled release-dosage formulation. The invention may be useful for, but not limited to, delivering pharmaceutically-active agents which include peptides (e.g. insulin), glycoproteins (e.g. erythropoietin), organic and inorganic chemicals (e.g. glyburide or steroids), herbals (e.g. vinca alkaloids), and other materials useful as pharmaceutically active agents.
For example, diabetes mellitus is a chronic disorder affecting carbohydrate, fat and protein metabolism. It is generally characterized by high blood sugar level (hyperglycemia) and sugar in urine (glycosurea) from a defective or deficient insulin secretory response. In the United States, over 10 million people are diagnosed as diabetics and this figure is increasing annually at a rate of about 6%. Two major variants of the disease exist. For about 10% of diabetics, the disease onsets as a juvenile insulinopenic diabetes requiring daily injection of insulin (referred to herein as insulin dependent diabetics or IDDM). The majority of diabetics are adult-onsetting diabetics (referred to herein as non-insulin dependent or NIDDM) for whom oral antihyperglycemics may be introduced to control hyperglycemia and glycosurea. Such compounds include chlorpropamide, tolbutamide (the first generation group of sulfonylureas), glyburide and glipizide (the second generation group). The sulfonylureas are believed to stimulate the beta cells of the pancreas, causing secretion of an endogenous insulin, and are also known to reduce hepatic production and to increase peripheral muscular utilization of glucose.
Ultimately, however, sulfonylureas will become less effective and eventually totally ineffective in lowering blood sugar in many long-term NIDDM patients, thus requiring injections of insulin as well, which causes restoration of the bioactivity of the sulfonyl urea (e.g. glyburide). According to one embodiment of the present invention, insulin-containing compositions of this invention, glyburide-containing compositions of this invention, and their combination markedly improved the bioavailability and activity of glyburide and oral insulin in NIDDM patents, who typically resist commercial glyburide and thus require daily injections of insulin.
Another embodiment of the present invention is directed to trans-umbilico dermal (referred to herein as TuD) delivery systems of the above-described compositions in human beings. More specifically, the TuD drug delivery system is concerned with well protected pharmaceutically-active agent or agents prepared in accordance with the compositions of this invention which are channeled into the liver, where the protected agent is released at a slow controlled rate, inducing the bioactivity of such compounds. In accordance with the present invention, the composition or compositions are applied on the dermal area of the human navel, that is the falciform ligament (paraumbilical veins) and its related system. The falciform ligament and Lig. teres in the liver, which are connected to tributaries of the epigastric veins and around the umbilicus, form anastomoses between the portal and the systemic venous systems. The umbilical foci is different from ordinary dermal layers. It is an artificially made scar tissue, having a thin epidermal layer with a direct connection to the falciform ligament (paraumbilical veins) and the epigastric vein. After applying the compositions of the present invention via the trans-umbilico-dermal delivery system to the navel foci, the compositions are rapidly and readily absorbed via the falciform ligament, and distributed within the liver and the systemic venous system. The trans-umbilico-dermal delivery of compositions of the present invention may also be employed as a means of targeting cancer chemotherapeutics (e.g. doxorubicin) into the liver, uterus, ovaries, lungs, the gastrointestinal system including the stomach, rectum, colon, etc. as well as other organs and systems.
By replacing inhibitors (e.g. nonulosaminic acid) with potentiators (e.g. a triantennary galactose terminated cholesterol), an affinity to the macrophageal system may be modified and it is possible to make compositions of this invention which can be predominantly channeled into the liver and other reticuloenthothelial systems (RES), thereby modifying the bioactivity of the pharmaceutically active agents employed while the systemic blood concentrations of such agents are kept at relatively low, non-toxic, non-side effect-inducing levels. Such hepato-specific delivery system-bound compositions may be given orally, rectally, trans-umbilico-dermally, parenterally or by other means. The therapeutic efficacy (i.e. the ratio between the side effect or toxic dose over the effective dose) of the agent may be increased by its binding in accordance with this invention. This may be exemplified as follows: disulfiram is biotransformed in the liver, forming an active diethyl dithiocarbamic acid; benzamidosalicylate forms amino-salicylic acid; biguanide forms cycloguanil; diazepam forms oxazepam; imipramine forms desipramine; phenacetin is activated in forming paracetamol; phenytoin forms di-phenyluredoacetic acid, and so forth. Also, the therapeutic effectiveness of pharmaceutically active agents may be induced by their transportation into the liver, where the agent or agents are actively biotransformed into therapeutically effective agents. For example, the antimalarial activity of primaguine as a pharmaceutically active agent is increased by its intrahepatic biotransformation into quinone derivatives while the side effects are reduced.
The present invention is dissimilar from other types of drug or pharmaceutical agent delivery systems. For example, compared to other routes, oral administration of compositions of the present invention containing insulin are more acceptable and convenient for diabetics. More particularly, absorption of insulin from the intestines to cause lowering of blood glucose levels has been reported when pancreatic enzymes are inactivated (Inouye, W. Y. et al. in Surg. Forum 13:316 (1962); Danforth, E. et al. in Endocrinology 65:118 (1959); and Crane, C. W. et al. in Diabetes 17:625 (1968)). However, the absorption of non-degradated insulin was found to be poor. To promote absorption of the macromolecules (e.g. insulin) from the intestinal membrane, surfactants, triglycerides, and lipid-surfactant mixed micelles have been reported with poor or unsatisfactory results (Muranishi, S. et al. in J. Pharm. Dyn. 1:28 (1978); J. Pharm. Dyn. 2:286 (1979); Int. J. Pharm. 4:219 (1980); Inouye et al., Danforth et al., and Crane et al.).
Insulin and a few adjuvants (anticholinergics) have been combined with a non-ionic surfactant (i.e. BRIJI 98), causing absorption of insulin; however, the minimum effective dose of insulin in human beings was too large (Galloway, J. A. et al. in Diabetes 21:637 (1972)). The non-ionic surfactant BRIJI 58 combined with insulin was found to be effective in increasing intestinal absorption of insulin, but the effective dose of insulin required was too large (Meshia, M. S. et al. in J. Pharm. Pharmacol. 33: 733 (1981)). After a water-oil-water (w-o-w) emulsion form of insulin was administered into a ligated jejunal pouch in rabbits, less than 8% absorption of insulin was reported, which was increased to about 58% of absorption of insulin administered as w-o-w micelle into the ligated jejunal pouch (Kawamori, R. and Shichiri, M. in Diabetes (1982) in Int. Cong. Ser. 600:315 (1983)). An oral insulin in nanoparticles was reported in Oppenheim, R. C. et al., Drug Dev. Ind. Pharm 8:531 (1982), but a large dose of insulin was needed. (Galloway et al.; Meshia et al.; Kawamon et al., Int. Cong. Ser. 600:315 (1983); Oppenheim et al.).
U.S. Pat. No. 4,146,499 (Rosano) discloses several methods for preparing oil-in-water (o-in-w) forms of microemulsion systems by applying an amphiphatic surfactant into the oil phase, and a second surfactant having its HLB value above the primary surfactant into the aqueous phase of water or buffer solutions. The oil soluble substance is dissolved in the solvent (e.g light mineral oil) having low boiling hydrocarbons (e.g. hexane), halocarbons containing a hydroxy group (e.g. carbon tetrachloride), and water immiscible oxygenated hydrocarbons (e.g. diethyl ether). The dispersion of the oils into the aqueous solvent converts the lactescent in dispersion into a microemulsion. No data on its biologically applicable efficacy are given.
Although the oral insulin forms obtained from the above-cited references may be absorbed from the intestinal membrane with limited efficiency, they apparently are inactivated at the liver and cleared by various macrophageal systems, which may include the Peyer's patch, various circulating scavenger blood cells, lymphoid tissues, the reticulo-endothelial systems, and others.
U.S. Pat. No. 4,579,730 (Kidron et al.) discloses a pharmaceutical composition for the oral administration of insulin which comprises insulin, bile salt or its derivatives and a protease-inhibitor. The composition can be enterocoated not only to protect the delivery system in the stomach but also to make the mixture slow release within the intestinal tract, and after its oral absorption from the intestinal membrane, enable delivery through the portal vein into the liver. The formulation disclosed in Kidron may not survive in the liver, as there are no means of protecting the system in the liver (other than the protease-inhibitor added), and Kidron's sustained-releasing form for insulin in the intestine would cause it to be too slowly absorbed. Biological test results of the oral insulin disclosed in Kidron were found to be poor and even less active than some other systems of applying surfactants, such as micelle, o-in-w emulsions and others (Muranishi, S. et al.; Galloway, J. A. et al.; Kawamori, R. et al.). In contrast, in the present invention only nonionic surfactants are employed in conjunction with the water soluble or miscible sterol and phospholipid bound microparticles suspended in micelle.
Significantly altered pharmacokinetics and efficacy of a polyglycol suspension of glyburide after oral or intravenous infusion was reported by Roger, H. J. et al. in Diabetologia 23:37 (1982). A micelle-forming polymeric adriamycin was made by using polyethyleneglycol and polyaspartic acid, which prolonged the survival time of cancerous mice while toxicity was reduced (the particle size was about 46 nm measured by laser scattering). Also, the system decreased antigenicity and prolonged its half-life in the circulating blood. It is also known that polyethyleneglycol is a nontoxic, nonimmunogenic water soluble and biodegrading polymer, as disclosed by Yokoyama, M. et al. in Makromol. Chem. 8:431 (1987). This system was intraperitoneally injected into the mice. Water soluble and targetable polymeric drug carriers based on N-(2-hydroxypropyl)methacryl-amide (HPMA) were bound with, for example, 5-aminosalicylic acid and galactosamine as the targeting moiety to cancer cells, as reported by Kopecek, J. in Advanced Drug Deliv. System 4 (ed. by Anderson, J. M. et al., at 279-290 (1990)). In contrast, the present invention is not used in conjunction with any polymeric or co-polymeric systems, and is effective for oral or TuD delivery of peptides.
Liposomes have been used as an oral delivery system for insulin. However, liposomes have shown a lack of dose-responsiveness, and inter- and intra-patients variations in the bioavailability and efficacy of insulin were noticed (Patel, H. M. et al. in FEBS Letters 62:60 (1976); Dapergolas, G. et al. in Lancet 2:824 (1976)). A modified liposome and a multiple emulsion has been disclosed in Eur. Pat. Appln. No. 0140085 (Yoshida). A drug containing lipid vesicle was prepared by stir-mixing an aqueous solution with phospholipids containing lipophilic surfactant. The lipid vesicles were dispersed in a dispersion medium and were freeze or spray dried (Patel et al.; Dapergolas et al.).
Europ. Pat. Appl. No. 0277776 (Huang) discloses a solid core liposome obtained by encapsulating a polymer mixture of emulsified warm (70.degree. C.) aqueous agarose and gelatin used as a topical or local administration as a sustained release drug carrier for an enzyme or peptide. This is similar to the system disclosed in U.S. Pat. No. 5,250,236 (Gasco), discussed further herein.
U.S. Pat. No. 4,536,324 (Fujiwara et al.) discloses a lipovesicle form made by dispersing a nonionic surfactant into a hydrophilic or hydrophobic component in an isolated state from an aqueous dispersion medium. The vesicle is formed by polyoxyethylene castor oil ethers and polyoxyethylene hardened castor oil ethers in the presence of sorbitan polyesters of long chain (C14-C18) fatty acids. An oil component of cosmetics may be contained in the vesicle, which has as its membrane component a lipophilic surfactant.
U.S. Pat. No. 4,348,384 (Horikoshi et al.) discloses a pharmaceutical liposomal formulation containing coagulation Factor-VIII or IX and a protease inhibitor. The liposome forming materials were egg yolk lecithin, phosphatidic acid or phosphatidylserine (to improve the stability and forming ability of liposome), cholesterol (to strengthen the liposomal membrane), lyso-lecithin (to promote the fusion of the liposomal membrane with the membrane of absorptional cells), and phosphatidic acid (to enlarge the particle sizes of liposome).
However, Fujiwara et al.'s lipid vesicles and Horikoshi et al.'s liposome are entirely different from the phospholipid-bound pharmaceutically-active agents in the form of microparticles suspended in micelle of the present invention. Horikoshi et al. selected negatively charged phosphatidic acid (referred to herein as PA) or phosphatidylserine (referred to herein as PS), which was bound with a cholesterol moiety. These elements together may possibly mechanically stabilize and strengthen the liposomal membrane. However, in the present invention, the pharmaceutically active agent-containing microparticles are prepared by using a water soluble or miscible phospholipid (noncovalently bound with the agent) and then bound to a water soluble or miscible sterol, in conjunction with a lipid soluble or miscible phospholipid. For example, in the present invention a lysophospholipid (referred to herein as lyso-PL) such as lyso-phosphatidylcholine (referred to herein as lyso-PC) may be used to improve the adherence of the microparticle to the membrane of absorptive cells and to enable and induce an additive effect with the surfactants in a physiological manner without inducing any histopathological damage to intestinal membranes, which are known to be induced by lyso-PC at relatively higher concentrations, e.g. 0.01-1 mM (Tagesson, C. et al. in Gut. 26:369 (1985)).
French Pat. No. 85-06998 (Tressens) discloses a multivesicular liposome where the lipid phase consists of phosphatidylethanolamine (PE), cholesterol, PS, trioleine in chloroform and ether, while the aqueous phase contains an insulin--maltose solution. The multivesicular liposome was lyophilized and packed into intestinal capsules. In contrast, in the present invention the pharmaceutically active agent (e.g. insulin) is reversibly bound and made into a micro-particle comprising a phospholipid such as a glycerophospholipid. The present invention is neither a liposome nor a multivesicular liposome.
U.S. Pat. No. 4,855,090 (Wallach) discloses multilamellar lipid vesicles (liposomes) having a high encapsulating mass and volume for hydrophilic or lipophilic materials. The lipophilic phase contains a surfactant (e.g. polyoxyethylene fatty ethers, polyoxyethylene cetyl ether, lauryl ether) with a sterol (e.g. cholesterol) and a charge producing amphiphile having a higher melting point than that of the surfactants. No biological data are given to indicate any efficacy of the claimed formulae in delivering peptides.
European Pat. Appl. No. 143,949 (Nakagama et al.) discloses a conventional liposome applying hydrogenated naturally occurring phospholipids to obtain a stable form of liposome. A fatty acid, preferably oleic acid at above 10 w % but preferably below 15 w % yields the most stable form of liposome capable of holding a drug within. Under these conditions, lecithin at its optimal weight percentage will form a lamellar liposome having oleic acid in the middle. However, at higher weight percentages of oleic acid, the phospholipids will form a micelle with oleic acid in the core, not a liposome. As disclosed by Wallach, Nakagama et al. applied cholesterol and tocopherol to strengthen the physical stability of the liposomal membrane, and applied negatively charged materials to achieve a slow releasing liposomal formulation within the body. After an intravenous infusion of liposomes containing 10,000 U of urokinase, a slow and sustained release of urokinase was observed in rabbits.
Both Wallach's and Nakagama et al.'s compositions are different from the compositions of the present invention. For example, both Wallach and Nakagama et al. have applied cholesterol, in combination with tocopherol and oleic acid, to strengthen liposomal membranes, and both have also applied a series of charged phospholipids, but neither have directly treated pharmaceutical agents such as peptides or drugs with, for example, phospholipids or cholesterol, although they have added surfactants.
In addition, in one embodiment of the present invention, microparticles comprising the pharmaceutically active agent urokinase (referred to herein as uPA) may be made by using glycerophosphorylcholine (referred to herein as GPC) and a water soluble cholesterol in the presence of a nonionic surfactant having an HLB value of above 15, and the microparticles are suspended in micelle in a fatty acid having a chain length of C.sub.14 or less (referred to herein as MCT). A small amount of PC and/or PS may be added together with another nonionic surfactant (having an HLB value of less than 6). The liposomal uPA of Honda and Nakagama et al. is believed to be absorbed via alpha-glycerophosphate pathways which are involved in intramembranous syntheses of chylomicron, apoproteins, etc. and drained through the lymphatics. However, in the present invention, the uPA-containing microparticles in micelle (and not in liposome), for example, are believed to be (and preferably are) absorbed via the monoglyceride pathways (as is MCT) and channeled into the portal system.
U.S. Pat. No. 4,849,227 (Cho) disclosed a system in which a pharmaceutically active peptide was "pinned" into solid cholesterol granules in the presence of sodium lauryl sulfate, coated with a solution containing mono-, di-, or tri-glycerides and fatty acids; coated with water soluble materials, e.g. hydroxypropylcellulose, and enteriocoated. The resultant dried powder was packed into a hard gel capsule or made into a pressed tablet. The absorbed cholesterol-bound insulin was believed to form chylomicron in vivo. It was found to be bioavailable and bioactive in some diabetics: i.e. an oral insulin dosage between 0.33-0.74 U/kg (average 0.5U/Kg) effectively lowered blood sugar and increased serum insulin levels.
PCT Pat. Appl. PCT/GB91/00510 (Cho) discloses the oral delivery of peptides by the integration of peptides with specially selected, neutrally charged phospholipids and apoproteins (e.g. apoprotein B48, AI, AII, etc.) or those known precursors of in vivo formation of such apoproteins (e.g. oleic acid, etc.). It is believed that membrane-integrating compounds are associated with the biologically active materials and integrated into forming the membrane system of chylomicron. Chylomicron forms a remnant chylomicron in the blood circulatory system, which is channeled into the liver. Thus, a peptide (e.g. insulin) bound with the membrane system of chylomicron may be channeled into the liver. Such a system is absorbed and forms part of a chylomicron, and is distinguishable from the disclosures of Wallach and Nakagama et al., in that neither Wallach nor Nakagama et al. are directed to formation of the membrane of remnant chylomicron.
The present invention, for use in oral insulin formulations and other applications, is significantly different from all the above-cited disclosures. For example, in cholesterol--and the phospholipid-bound insulin microparticles in micelle embodiment of this invention after oral or TuD administration, the composition is absorbed and predominantly channeled into the portal system and then the liver as well as systemic circulation.
In the above-cited disclosures, various lipids and/or surfactants are used to deliver (orally or otherwise) peptides/drugs through mechanisms of known or as yet unknown transmembranous absorptions. Such mechanisms may involve, e.g. liposomes, lipospheres, lipoprotein-microparticles, lipid vesicles, and others, which are predominantly known to involve syntheses of chylomicron, apolipoproteins, lipoproteins or others within the absorptive membrane, and which are ultimately drained through the lymphatic vessels and thoracic duct. The overall absorption of such peptides/drugs by applying the above described formulations may be sporadic, erratic, unpredictable, and lacking uniformity in terms of bioavailability. This is expected from the characteristic physiological flow-kinetics of lymph fluids from the thoracic duct as the lymph fluid outflow from the thoracic duct is sporadic and not a uniform steady flow.
More particularly, PCT Patent Application PCT/GB91/00510 (Cho) discloses oral delivery systems for peptides, such as insulin, by dissolving the insulin into a hydrophilic solution, which contains a surfactant having an HLB value of 14 or above, and a lipophilic solution containing cholesterol:PC (at usually 6-8:1 ratio), apolipoproteins, 50 w/v % or more of oleic acid to hopefully enhance an in vivo syntheses of apoprotein, chylomicron, lipoproteins, etc. at the intestinal membrane, involving the glycerophosphate pathways. In the present invention, the water soluble-phospholipid bound microparticles are suspended in MCT micelle. However, the solutions of Cho (PCT/GB91/00510) were microfluidized and made into a microemulsion.
Gasco discloses formulations containing various drugs in solid lipid microspheres. More particularly, Gasco discloses a microemulsion prepared by contacting a molten lipid (which may contain a drug) with a mixture of water and surfactant heated to the lipid's melting temperature, and dispersing the microemulsion in water to create a lipid microsphere dispersion. It is believed, based upon the disclosure of Gasco, that such microspheres resemble a liposome described by Fabre, H. et al. in J. Phys. Chem. 85: 3493, (1981). Gasco also discloses lyophilization of the microsphere dispersion. However, it is believed that any freeze-drying or heating of an emulsion, microemulsion, liposphere, liposome, lipid vesicle, micelle, or solid emulsion (e.g. U.S. Pat. No. 4,849,227 (Cho)) will cause irreversible damage to the system and may deteriorate the bioactivities of the pharmaceutically active agents, especially peptides, glycoproteins, etc. Gasco does not disclose any biological data after applying the lipospheres containing deoxycorticosterone, salbutamol, salmon calcitonin, somatostatin, and erythropoietin. It is believed that these compounds may be partially inactivated by heating together with the fatty acids applied by Gasco.
In addition, there are no related known disclosures relating to the embodiment of the present invention wherein trans-umbilico-dermal delivery of the compositions of this invention is employed. Other formulations and methods for delivery of drugs or peptides, although different than the present invention, are summarized as follows:
Liu, J. C. in Internat. J. Pharm. 44: 197 (1988) applied an iontophoresis of d.c. current of various wave form to facilitate and regulate the transdermal ("TD") delivery of insulin in rats. U.S. patent application Ser. Nos. 804661 and 899049, now U.S. Pat. No. 5,023,252 (Hsieh) disclose anhydrides and esters of macrocyclic lactone and ketones at 0.1-30 wt. % as a TD enhancer for a drug (e.g. triamcinolone acetonide). U.S. Pat. No. 4,649,075 (Jost) discloses a foam device which is a disk on a truncated inverted cone of macroporus cellular polymer core containing insulin, nonoxylnol-9, ocotoxynol, etc. and an outlayer containing a microporous cellular polymer. Makino, Y. et al. (Japan Pat. Appl. 84/182724) have used pyroglutamates as a dermal penetrating enhancer for TD delivery of indomethacin. PCT Publication No. WO 85/05036 (Weber, C. J. et al.) discloses the use of 33-50% DMSO and 2.5% of HPMC gel as a penetrating enhancer for TD delivery of insulin. M. Ferreira Mouta, Jr. (Braz. Pedido PI BR 84/1369 A) discloses mixed insulin with an oily excipient and incorporated with a plaster for TD delivery of insulin. Nagai, T. J. in Controlled Release 2:121 (1985) has incorporated triamcinolone with carbopol-934, a brand of carbomoer, and applied it on an adhesive layer of HPC for buccal mucosal delivery of insulin. German Pat. No. DE 3406497 (Franzky et al.) discloses dissolved isosorbide dinitrate in a mixture of polyethyleneglycol-glycerin partial ester with oleic acid, glycerin partial ester with capric and caprylic acids, isopropyl palmitate and water in the presence of a surfactant having an HLB value of 8 and cosurfactant having an HLB value below 8, and applied isosorbide for use as a trans-dermal (TD) system. Kazim, M. et al. in Surg. Forum 35: 64 (1984) has mixed insulin with the penetration enhancers DMSO and n-decylmethyl sulfoxide, and applied the mixture over the skin of streptocin-induced diabetic rats, covered it with a nonporous polyethylene patch, and observed antihyperglycemic effects in rats.
The above and other cited references have not made any disclosures of any compositions useful in transdermal applications of compositions which are similar to the compositions of the present invention. More particularly, the dermal areas on which these other TD formulations were applied are entirely different from the embodiment of the present invention which is specifically concerned with a trans-umbilico-dermal application of compositions of the present invention via falciform ligament and its anatomically associated system.
In the early 1980s, the Belmac firm of Tampa, Fla., developed a "navel drop" which consisted of camphor which was dropped into the navel foci, was absorbed through the falciform ligament and its related system into the mesenteric and portal vasculatures, induced a vasodilation and was supposed to have improved hemorrhoidal conditions in humans. Camphor, among other compounds, causes cutaneous vasodilation (Bowman, W. C. & Rand, M. J. in Textbook of Pharmacology, 2nd ed., p. 16.3 (1980)). Therefore, after dropping the navel drop (camphor) into a human navel, its being a cutaneous vasodilator, it is readily absorbed via the falciform ligament and its surroundings. However, an administration of any other TD forms of macromolecules or drugs, unlike the pure camphor, may not be readily absorbed through the falciform ligament. Such a TD formulation has to be modified specifically for the trans-umbilico-dermal delivery system. The trans-umbilico-dermal delivery system embodiment of the present invention and the "navel drop" containing camphor as its main component are thus entirely different, as the present invention relates to transdermal delivery formulations for pharmaceutically-active agents (e.g. peptides or drugs) which may be effectively administered via the falciform ligament.
The micelles of this invention, like compounds such as glycerol and fatty acids having a chain length of less than about C.sub.14, monoglycerides, diglycerides, and the products of triglyceride hydrolysed by pancreatic lipase (e.g. 2-monoglycerides) are believed to be absorbed, via monoglyceride pathways, readily and rapidly from the cellular membrane by a passive diffusion mechanism, and are directed into the portal system. The absorption of relatively large and completed systems, as discussed by Larsen, K. et al. in Chem. Phys. Lipid, 12:321 (1980) or, e.g. an infinite periodic minimal surface (IPMS) as discussed by Longley, W. et al. in Nature 303:612 (1983) may be by a mechanism grossly similar to those involving pinocytosis or endocytosis. However, in such a mechanism the absorbed lipid apparently does not involve alpha-glycerophosphate pathways but rather the emonoglyceride path and is thereby channeled into the portal system. This is different from the known mechanism of absorption of fatty acids having a chain length of C.sub.16 and above (referred to herein as LCT), emulsions, liposomes, lipid vesicles, lipospheres, etc. which are absorbed via the alpha-glycerophosphate pathways at the membrane, are involved in syntheses of chylomicron, membranes for chylomicron, lipoproteins, apoproteins and others at the cell membrane, and are channeled through lymphatics into the thoracic duct. LCT are primarily absorbed from the cell membrane by pinocytoses or other as yet unknown mechanisms. An involvement of Pyer's patch at the small intestinal membrane, for the absorption of IPMS, liquid-crystalline phase of micelle, etc., is a plausible hypothesis. (Larson et al.; Longley et al.).
Without wishing to be bound by any one theory, it is believed that after the microparticles (containing a pharmaceutically active agent) in micelle of this invention are absorbed by the human body, they are channeled into the portal system. The formulation may contain one or more inhibitors for reticuloenthothelial system (RES) activity. The invention is capable of being passed through the absorptive columnar enterocytes, the Pyer's patch and others. The pharmaceutically active agent may thus be channeled into the portal system. When a fatty acid having a chain length of C.sub.14 or less (referred to herein as MCT), a lysophospholipid (referred to herein as lyso-PL), and a fatty acid salt are added into the water, a lamellar L-alpha (lamellar or liquid crystalline) phase of the micelle is formed. At relatively high lipid concentration of the micelle, in the presence of phosphatidylcholine (PC), sphingomyelin, phosphatidyiserine (PS), etc., the spherical micelle is transformed into a rod shaped micelle. When the lipid concentration is increased further, especially in the presence of cardlollpin, phosphatidic acid (referred to herein as PA), a hexagonal lipid cylinder (liquid crystalline phase, or H1) is formed. It is possible to formulate, e.g. by using PC, a lamellar liquid crystalline phase with solvents other than water, such as ethylene glycol, and properly secreted surfactants. The spherical, rod-shaped, lamellar L-alpha or liquid crystalline phases may be obtained by simply altering the concentrations and the types of lipids used, by changing the temperature of solvents used, by selecting appropriate phospholipids, (referred to herein generally as PL), by changing the fluidity of protein-bound lipids, etc. These various phases involving the lipids-water (or other selected solvent) interactions, are generally known as micelle. (Larsson, K. et al. J. Colloid, Interface Sci. 72: 152, (1979); El-Nokaly, M. et al., J. Colloid Interface Sci. 84:228 (1981)).
A microemulsion is the reversed type of liquid phase of an ordinary L1 phase micelle. For example, water aggregates in a continuous hydrocarbon chain medium and water lamellae are separated by lipid bilayers (L2 phase) in aqueous systems of polar lipids and triglyceride oil. In the presence of, for example, lyso-phophatidylcholine (referred to herein as lyso-PC) it becomes a microemulsion. Liposomes are formed when water is added into the lamellar liquid-crystalline phase at above its swelling limit by gentle stirring. The lamellar liquid crystalline phase may consist of concentric lipid bilayers alternating with water layers. Sonicating the unilamellar aggregates under certain conditions may yield lipid vesicles. By further diluting the liposome, a so-called liposphere may be formed. The pharmacokinetic properties of a micelle, especially during its absorption from the cellular membrane and the transporting systems involved, are significantly different from that observed after introducing a pharmaceutically active agent within a liposome, microemulsion, lipid vesicle, liposphere, emulsion, or lipid suspension. (Ekwall, P., Advances in Liquid Crystals, Vol. 1, Chapter 1, Academic Press, N.Y. (1975)).
For example, in one embodiment of this invention, urokinase (referred to herein as uPA) is employed as the pharmaceutically active agent, the microparticles were made with specially prepared, water soluble cholesterol made in accordance with the method of Proksch et al. in Clin. Chem. 24/11:1924-26 (1978) (i.e. polyoxyethanyl-cholesteryl adipate, containing about 30% water soluble cholesterol and GPC, a water soluble enzymatically hydrolysed PC, i.e. sn-3-glycerophosphorylcholine, obtained after incuvating PC with its specific hydrolysing enzyme, phospholipidase-B, prepared by the method of Kates described in Techniques in Lipidology, Elsevier, Amsterdam (1972). The uPA in sodium phosphate buffer solution (pH 7.4) was bound with GPC:GPS (4:2-1 Mol ratio), and the water soluble cholesterol (4:2-1 Mol ratio of C:PC) in the presence of lyso-PC (i.e. sn-1-acyl-3-glycerophosphorylcholine, a lipid soluble end product of PC hydrolysed by phospholipidase-A2) and a nonionic surfactant (polyoxy-40-stearate), and made into microparticles in 15-20 v/v % of the final volume of MCT. The MCT contained another nonionic surfactant having an HLB value of less than 6. The MCT and above-described mixture were micronized to form uPA-containing microparticles suspended in MCT micelle. The overall bioavailability and bioactivity of the uPA-microparticles in MCT micelle was excellent. In addition, assaying for uPA from serum/plasma samples and for uPA microparticles in MCT-micelle, in vitro, using the ELISA method, was found to be easier when uPA was bound to GPC/GPS-water soluble cholesterol, as compared with when uPA was `bridge-locked` with PC, PA apoproteins cholesterol, etc., as disclosed for example in PCT/GB91/00510 (Cho), and Chung, K. H., Chung, J. S. & Cho, Y. W.: Presented at 13th Congress International Soc. Thrombosis & Homeostasis, Jul. 3, 1991, Utrecht. discussed above. The stability of this embodiment of the invention was good; however, it was further stabilized by adding less than 5 w/v % of LCT into the MCT-micelle, and by adding a small quantity of PC and PS, into the MCT solution.
In another embodiment of this invention, the pharmaceutically active agent is quinine which is contained within microparticles suspended in the MCT micelle. After oral or TuD administration and absorption, it is targeted to erythrocytes and hepatacytes hosting plasmodium malarial parasites which may utilize the components therein (i.e. microparticles containing quinine which are suspended in micelle to repair the damaged membrane of erythrocytes and hepatocytes. Also, microparticles containing vincristin have been successfully targeted to experimental IgM Immunocytoma cells in Wister rat and introperitoneally inoculated P388 mouse leukemic cells.
In one particularly, preferred embodiment, water soluble cholesterol is added as a sterol, to stabilize the microparticles in MCT micelle. Optionally, an LCT (i.e. having a chain length of C.sub.16 or higher, preferably C.sub.18 such as 1; 9-octadecenoic) may be added to the MCT micelle (at a concentration of 5 w/v % or less of the final MCT-micelle) to augment and stabilize the MCT-micelle. After adding properly selected surfactants to the LCT at or above the critical-micelle-concentration (CMC) (but preferably at or below 5 w/v %), a second micelle (i.e. LCT micelle) is formed. This LCT-micelle is compatible with the MCT-micelle containing the microparticles.
The objects and features of the present invention will be apparent from the following detailed description and the claims.